Mobile communications system, mobile communications method, server, transfer device, and mobile communications terminal

ABSTRACT

A mobile communications system for transferring packets to a mobile communications terminal according to address information of the mobile communications terminal is disclosed. The mobile communications terminal is located in a moving network connected to a given node in a core network. The address information of the mobile communications terminal includes common information related to the given node to which the moving network is connected, and individual information which is unrelated to the given node to which the moving network is connected and is unchanged when the given node to which the moving network is connected is changed.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application is based upon and claims the benefit of priorityfrom the prior Japanese Patent Application No. P2003-067195, filed onMar. 12, 2003; the entire contents of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a mobile communications system,a mobile communications method, a server, a transfer device, and amobile communications terminal for supporting moving networks.

[0004] 2. Description of the Related Art

[0005] A mobile communications system employing a Global v6 routingscheme is conventionally known as a mobile communications system forsupporting moving networks. A mobile communications system employing aHierarchical Mobile IP (HMIP) is also conventionally known as a mobilecommunications system for supporting moving networks.

[0006] In the mobile communications system employing the conventionalGlobal v6 routing scheme, when a moving network is performing a handoffprocess, it is necessary to notify home agents of all mobilecommunications terminals within the moving network, of the movement. Inthe mobile communications system, it is also necessary to notifyterminals as correspondent nodes of the movement, so as to implementroute optimization during the handoff process of the moving network.

[0007] As a result, the mobile communications system causes increases inthe amount of signals to be transmitted and handoff processing timeduring the handoff process of the moving network.

[0008] Specifically, as shown in FIG. 1, in the mobile communicationssystem, when a moving-network A moves, that is, when the connection toan access node AN to which the moving network A is connected is changedto another access node, address information of all mobile terminals(mobile communications terminals) MT #1 and MT #2 located in the movingnetwork A is changed. Hereinafter, the address information of the mobileterminal is called the mobile terminal address information.

[0009] In the example of FIG. 1, a connecting node of the moving networkA is changed from AN 1 to AN 2, and mobile terminal MT #1 addressinformation (Care-of-Address [CoA]) is changed from “AN1prefix+#1” to“AN2prefix+#1,” and mobile terminal MT #2 address information (CoA) ischanged from “AN1prefix+#2” to “AN2prefix+#4.”

[0010] At that time, in the mobile communications system, home agents HA1 and HA 2 of the mobile terminals MT #1 and MT #2 and mobile terminalsMT #3 and MT #4 as correspondent nodes are notified of the changedmobile terminal address information, thereby to be able to continuecommunication without breaking an optimized communication route.

[0011] In the mobile communications system, however, it is necessary tonotify all home agents and correspondent nodes of the movement of themoving network A, requiring a large amount of signals and muchprocessing time before the completion of update of the mobilecommunications terminal address information, and causing difficulty insupporting real time communication.

[0012] The mobile communications system performs Duplicate AddressDetection (DAD) to prevent the address information (CoAs) on the mobileterminals MT #1 and #2 from being the same as that on other mobileterminals. There is thus a possibility that a portion following“AN1prefix” (e.g., #2) will be changed in a CoA newly provided when themoving network moves, causing an increase in time required for theupdate of the mobile communications terminal address information.

[0013] A mobile communications system employing the conventional HMIP,in which, instead of all home agents and correspondent nodes, a MobilityAnchor Point (MAP) is notified of the movement of a moving network, isthus superior to the above-described mobile communications systememploying the Global v6 routing scheme.

[0014] In this mobile communications system, however, it is alsorequired to update address information of all mobile communicationsterminals located in a moving network when the moving network moves,preventing a substantial reduction in handoff processing time.

[0015] Specifically, as shown in FIG. 2, in the mobile communicationssystem, when a moving network A moves, that is, the connection to anaccess node AN to which a mobile node MN configured to manage the movingnetwork A is connected is changed to another access node, addressinformation of all mobile terminals (mobile communications terminals) MT#1 and MT #2 located in the moving network A is changed.

[0016] In the mobile communications system, the MAP placed in a corenetwork 1 holds pieces of next hop destination information (CoA_MN) fortransmission to all the mobile terminals MT #1 and MT #2 located in themoving network A, which information pieces are not correlated. It isthus required to transmit to the MAP individual update information onall the mobile terminals MT #1 and #2 located in the moving network Awhen the mobile terminal A moves, causing an increase in handoffprocessing time.

BRIEF SUMMARY OF THE INVENTION

[0017] The present invention has been made in view of the aboveproblems, and has an object of providing a mobile communications system,a mobile communications method, a server, a transfer device, and amobile communications terminal for supporting moving networks, whichallow significant reductions in the amount of signals and processingtime during handoff process.

[0018] A first aspect of the present invention is summarized as a mobilecommunications system for transferring packets to a mobilecommunications terminal according to address information of the mobilecommunications terminal. The mobile communications terminal is locatedin a moving network connected to a given node in a core network. Theaddress information of the mobile communications terminal includescommon information and individual information. The common information isrelated to the given node to which the moving network is connected. Theindividual information is unrelated to the given node to which themoving network is connected. The individual information is unchangedwhen the connection to the given node to which the moving network isconnected is changed to another node.

[0019] A second aspect of the present invention is summarized as amobile communications method of transferring packets to a mobilecommunications terminal according to address information of the mobilecommunications terminal. The mobile communications terminal is locatedin a moving network connected to a given node in a core network. Theaddress information of the mobile communications terminals includescommon information and individual information. The common information isrelated to the given node to which the moving network is connected. Theindividual information is unrelated to the given node to which themoving network is connected. A given mobile communications terminallocated in the moving network detects change of the given node to whichthe moving network is connected. The given mobile communicationsterminal changes the address information of all mobile communicationsterminals located in the moving network, only by changing commoninformation of the address information of the mobile communicationsterminals. The given mobile communications terminal notifies the mobilecommunications terminals located in the moving network of the change ofthe address information of the mobile communications terminals, andnotifies an address management device configured to manage addressinformation of the mobile communications terminals located in the movingnetwork of the change.

[0020] A third aspect of the present invention is summarized as a mobilecommunications method of transferring packets to a mobile communicationsterminal according to address information of the mobile communicationsterminal. The mobile communications terminal is located in a movingnetwork connected to a given node in a core network. The addressinformation of the mobile communications terminals includes commoninformation and individual information. The common information isrelated to the given node to which the moving network is connected. Theindividual information is unrelated to the given node to which themoving network is connected. The given node notifies a mobile nodeconfigured to manage the moving network of common information related tothe given node. The mobile node changes the address information of allmobile communications terminals located in the moving network, only bychanging common information of the address information of the mobilecommunications terminals according to the notified common information.The mobile node notifies an address management device configured tomanage the address information of the mobile communications terminals inthe moving network of the change of the address information of themobile communications terminals.

[0021] A fourth aspect of the present invention is summarized as aserver in a mobile communications system for transferring packets tomobile communications terminals according to address information of themobile communications terminal. The mobile communications terminals arelocated in a moving network connected to a given node in a core networkThe server has an address information manager configured to manage theaddress information of all mobile communications terminals located inthe moving network. The address information of the mobile communicationsterminals includes common information and individual information. Thecommon information is related to the given node to which the movingnetwork is connected. The individual information is unrelated to thegiven node to which the moving network is connected. The individualinformation is unchanged when the connection to the given node to whichthe moving network is connected is changed to another node.

[0022] A fifth aspect of the present invention is summarized as atransfer device provided on a packet transfer path in a mobilecommunications system for transferring packets to a mobilecommunications terminal according to address information of the mobilecommunications terminal. The mobile communications terminal is locatedin a moving network connected to a given node in a core network. Thetransfer device has an address information manager configured to relatethe address information of the mobile communications terminal located inthe moving network. The address information of the mobile communicationsterminal includes common information and individual information. Thecommon information is related to the given node to which the movingnetwork is connected. The individual information is unrelated to thegiven node to which the moving network is connected.

[0023] A sixth aspect of the present invention is summarized as a mobilecommunications terminal in a mobile communications system fortransferring packets to mobile communications terminals located in themoving network connected to a given node in a core network according toaddress information of the mobile communications terminals. The mobilecommunications terminal has an address information manager configured tomanage the address information of the mobile communications terminalslocated in the moving network. The address information of the mobilecommunications terminals includes common information and individualinformation. The common information is related to the given node towhich the moving network is connected. The individual information isunrelated to the given node to which the moving network is connected.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0024]FIG. 1 is an entire block diagram of a mobile communicationssystem according to a conventional art;

[0025]FIG. 2 is an entire block diagram of a mobile communicationssystem according to a conventional art;

[0026]FIG. 3 is an entire block diagram of a mobile communicationssystem according to a first embodiment of the present invention;

[0027]FIG. 4 is a functional block diagram of a mobile terminal in themobile communications system according to the first embodiment of thepresent invention;

[0028]FIG. 5 is a functional block diagram of a mobility managementrouter in the mobile communications system according to the firstembodiment of the present invention;

[0029]FIG. 6 is a functional block diagram of a mobility managementserver in the mobile communications system according to the firstembodiment of the present invention;

[0030]FIG. 7 is a sequence diagram illustrating a registration operationof a mobile terminal in the mobile communications system according tothe first embodiment of the present invention;

[0031]FIG. 8 is a sequence diagram illustrating an operation of changingmobile terminal address information of the mobile communications systemaccording to the first embodiment of the present invention;

[0032]FIG. 9 is an entire block diagram of a mobile communicationssystem according to a second embodiment of the present invention;

[0033]FIG. 10 is a functional block diagram of a mobile node in themobile communications system according to the second embodiment of thepresent invention;

[0034]FIG. 11 is a sequence diagram illustrating an operation ofchanging mobile terminal address information of the mobilecommunications system according to the second embodiment of the presentinvention;

[0035]FIG. 12 is an entire block diagram of a mobile communicationssystem according to a third embodiment of the present invention;

[0036]FIGS. 13A and 13B are diagrams illustrating exemplary locationinformation managed in the mobile communications system according to thethird embodiment of the present invention;

[0037]FIG. 14 is an entire block diagram of a mobile communicationssystem according to a fourth embodiment of the present invention;

[0038]FIG. 15 is an entire block diagram of a mobile communicationssystem according to a fifth embodiment of the present invention;

[0039]FIG. 16 is a functional block diagram of a network managementserver in the mobile communications system according to the fifthembodiment of the present invention;

[0040]FIG. 17 is a sequence diagram illustrating a registrationoperation of a mobile terminal in the mobile communications systemaccording to the fifth embodiment of the present invention;

[0041]FIG. 18 is a sequence diagram illustrating a packet transferoperation in the mobile communications system according to the fifthembodiment of the present invention; and

[0042]FIG. 19 is a sequence diagram illustrating an operation ofchanging mobile terminal address information of the mobilecommunications system according to the fifth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

[0043] <Configuration of Mobile Communications System in a FirstEmbodiment of the Invention>

[0044] The configuration of a mobile communications system according toa first embodiment of the present invention will be described withreference to FIGS. 3 to 6.

[0045] As shown in FIG. 3, the mobile communications system of thisembodiment has a plurality of access nodes AN 1 to AN 5, a mobilitymanagement router 30, and mobility management servers 50, 50 a and 50 b,within a core network 1.

[0046] In the example of FIG. 3, a moving network A comprised of aplurality of mobile terminals including MT #1 and MT #2 is moving from astate of connection with the access node AN 1 into a state of connectionwith the access node AN 2.

[0047] In the mobile communications system of this embodiment, as shownin FIG. 3, packets are transferred to the mobile terminals (mobilecommunications terminals) MT #1 and MT #2 located in the moving networkA connected to a given node (the access node AN 1 or AN 2) within thecore network 1, based on address information of the mobile terminals(mobile communications terminals) MT #1 and MT #2.

[0048] As shown in FIG. 3, mobile terminal address information ofcludescommon information and individual information.

[0049] The common information is related to a given node (the accessnode AN 1 or AN 2) to which the moving network A is connected.

[0050] The individual information is unrelated to the given node (theaccess node AN 1 or AN 2) to which the moving network A is connected.The individual information is unchanged when the connection to the givennode (the access node AN 1 or AN 2) to which the moving network isconnected is changed to another node (the access node AN 1 or AN 2).

[0051] More specifically, when the moving network A is connected to theaccess node AN 1, the mobile terminal MT #1 address information is“AN1prefix (common information)+#1 (individual information)”. When themoving network A is connected to the access node AN 2, the mobileterminal MT #1 address information is “AN2prefix (common information)+#1(individual information)”.

[0052] Likewise, when the moving network A is connected to the accessnode AN 1, the mobile terminal MT #2 address information is “AN1prefix(common information)+#2 (individual information)”. When the movingnetwork A is connected to the access node AN 2, the mobile terminal MT#2 address information is “AN2prefix (common information)+#2 (individualinformation)”.

[0053] As described above, the common information (AN1prefix orAN2prefix) is changed, depending on whether the moving network A isconnected to the access node AN 1 or the access node AN 2.

[0054] As shown in FIG. 3, packets transmitted from the mobile terminalMT #3 or MT #4 are transferred via the mobility management router 30 tothe mobile terminal MT #1 or MT #2 located in the moving network A.

[0055] Here, the mobility management router 30 is provided on a packettransfer path formed not to have a redundancy like a packet transferpath including a fixed-location home agent.

[0056] When detecting the movement of the moving network A, the mobileterminal MT #1 located in the moving network A notifies, on behalf ofall the mobile terminals MTs located in the moving network A, themobility management router 30 and the mobility management server 50, ofan update information (a binding update) on the address information ofall the mobile terminals MTs located in the moving network A.

[0057] Now, with reference to FIG. 4, the configuration of the mobileterminal MT #1 located in the moving network A will be described.

[0058] As shown in FIG. 4, the mobile terminal MT #1 has an informationreceiving unit 11, a individual information managing unit 12, a locationinformation generating unit 13, an information transmitting unit 14, anda location-in-moving network information managing unit 15.

[0059] The information receiving unit 11 receives an advertisement(broadcast information) transmitted from the access node AN 1 or AN 2and a binding update (update information) transmitted from anothermobile terminal such as MT #2.

[0060] The individual information managing unit 12 manages theindividual information on the mobile terminal MT #1. In the exampleshown in FIG. 4, the individual information managing unit 12 managesindividual information “#1” on the mobile terminal MT #1. The individualinformation is unchanged when a connecting access node of the movingnetwork A is changed from the access node AN 1 to the access node AN 2.

[0061] At the beginning of existing in the moving network A, thelocation information generating unit 13 generates location information(address information) on the mobile terminal MT #1, based on commoninformation included in the advertisement received from the access nodeAN 1 or AN 2 and the individual information managed by the individualinformation managing unit 12.

[0062] The information transmitting unit 14 transmits the locationinformation generated by the location information generating unit 13, tothe mobility management router 30 and the mobility management servers50, 50 a and 50 b.

[0063] An information transmitting unit 14 of any other mobile terminalMT than the mobile terminal MT #1 transmits location informationgenerated by a location information generating unit 13 of the mobileterminal MT, to the mobile terminal MT #1 located in the moving networkA, the mobility management router 30, and the mobility managementservers 50, 50 a and 50 b.

[0064] The information transmitting unit 14 transmits an advertisementshowing a change of the mobile terminal MT #1 location information(address information), to all the mobile terminals MTs located in themoving network A. The advertisement includes changed common information,for example.

[0065] The information transmitting unit 14 also transmits a bindingupdate showing a change of the mobile terminal MT #1 locationinformation (address information), to the mobility management router 30and the mobility management servers 50, 50 a and 50 b. The bindingupdate includes changed common information, for example.

[0066] The location-in-moving network information managing unit 15manages location information (address information) on all the mobileterminals MTs located in the moving network A.

[0067] Specifically, the location-in-moving network information managingunit 15 constitutes an address information manager configured to managethe location information (address information) on the mobile terminalsMTs located in the moving network A.

[0068] When detecting that the connection to an access node AN (givennode) to which the moving network A is connected is changed to anotheraccess node, the location-in-moving network information managing unit 15changes the mobile terminal MT location information (addressinformation) by changing only the common information.

[0069] Now, with reference to FIG. 5, the configuration of the mobilitymanagement router 30 will be described.

[0070] As shown in FIG. 5, the mobility management router 30 has aninformation receiving unit 31, a location information managing unit 32,a notifying unit 33, and a routing processing unit 34.

[0071] The mobility management router 30 is a transfer device providedon a transfer path of packets to be transferred to the mobile terminalMTs located in the moving network A.

[0072] The information receiving unit 31 receives various informationincluding location information transmitted from a mobile terminal MTwhich begins to exist in the moving network A, and a binding updatetransmitted from the mobile terminal MT #1.

[0073] The location information managing unit 32 manages locationinformation of all the mobile terminals MTs located in the movingnetwork A.

[0074] In the example of FIG. 5, the location information managing unit32 manages mobile terminal MT #1 location information including “commoninformation=AN1prefix” and “individual information=#1”, mobile terminalMT #2 location information including “common information=AN1prefix” and“individual information=#2”, and so on.

[0075] The location information managing unit 32 changes the commoninformation of the mobile terminal MT location information it manages,according to a binding update from the mobile terminal MT #1, therebychanging the mobile terminal MT location information.

[0076] When a mobile terminal MT is newly located in the moving networkA, the notifying unit 33 notifies a correspondent node (e.g., the mobileterminal MT #3 or MT #4) communicating with the mobile terminal MT ofthe fact.

[0077] The routing processing unit 34 refers to the location informationmanaging unit 32, so as to transfer packets to a mobile terminal MTlocated in the moving network A.

[0078] In the example of FIG. 3, the routing processing unit 34transfers packets transmitted from the mobile terminal MT #3 via theaccess node AN 3, to the mobile terminal MT #1 via the access node AN 1.The routing processing unit 34 also transfers packets transmitted fromthe mobile terminal MT #4 via the access node AN 4, to the mobileterminal MT #2 via the access node AN 1.

[0079] The function of the mobility management router 30 may be providedto the access nodes AN 1 to AN 4, the mobile terminals MT #3 and MT #4as the correspondent nodes and the like.

[0080] Now, with reference to FIG. 6, the configurations of the mobilitymanagement servers 50, 50 a and 50 b will be described. As shown in FIG.6, the configurations of the mobility management servers 50, 50 a and 50b are basically the same, except for the details of management by alocation information managing unit 51. Thus, the function of themobility management server 50 will be hereinafter representativelydescribed.

[0081] As shown in FIG. 6, the mobility management server 50 has alocation information managing unit 51, an information receiving unit 52,and an information transmitting unit 53. The mobility management server50 is an MIP home agent, for example.

[0082] The location information managing unit 51 manages locationinformation of all the mobile terminal MTs located in the moving networkA.

[0083] In the example of FIG. 6, the location information managing unit51 manages mobile terminal MT #1 location information including “commoninformation=AN1prefix” and “individual information=#1”, mobile terminalMT #2 location information including “common information=AN1prefix” and“individual information=#2”, and so on.

[0084] The location information managing unit 51 changes the commoninformation of the mobile terminal MT location information it manages,according to a binding update from the mobile terminal MT #1, therebychanging the mobile terminal MT location information.

[0085] To reduce access during location information change, locationinformation managing units 51 a and 51 b of the mobility managementservers 50 a and 50 b are provided with pointers to the locationinformation managing unit 51 of the mobility management server 50.

[0086] More specifically, as shown in FIG. 6, the location informationmanaging unit 51 a of the mobility management server 50 a stores thefact that the mobile terminal MT #1 location information is listed in atable for the moving network A within the location information managingunit 51 of the mobility management server 50 (pointer information).

[0087] The location information managing unit 51 b of the mobilitymanagement server 50 b stores the fact that the mobile terminal MT #2location information is listed in the table for the moving network Awithin the location information managing unit 51 of the mobilitymanagement server 50 (pointer information).

[0088] Details of the mobile terminal MT #1 location information arestored in the location information managing unit 51 of the mobilitymanagement server 50.

[0089] During a handoff process of the mobile terminal MT #1 or MT #2,the location information managing unit 51 of the mobility managementserver 50 performs a rewrite of the information, while the locationinformation managing units 51 a and 51 b of the mobility managementservers 50 a and 50 b do not perform a rewrite of the information.

[0090] The information receiving unit 52 receives various informationincluding location information transmitted from a mobile terminal MTwhich begins to exist in the moving network A, and a binding updatetransmitted from the mobile terminal MT #1. The information transmittingunit 53 transmits various information. <Operation of the MobileCommunications System in the Embodiment>

[0091] The operation of the mobile communications system according tothis embodiment will be described with reference to FIGS. 7 and 8.

[0092] First, with reference to FIG. 7, description will be made on anoperation of assigning address information (location information), thatis, a registration operation of the mobile terminal MT #2, when themobile terminal MT #2 is newly located in the moving network A, in themobile communications system of this embodiment.

[0093] As shown in FIG. 7, in step 101, the access node AN 1 transmitsan advertisement including common information (AN1prefix) related to theaccess node AN 1.

[0094] In step 102, the location information generating unit 13 of themobile terminal MT #2 which has begun to exist in the moving network Agenerates location information (“AN1prefix”+“#2”), using the commoninformation included in the advertisement received from the access nodeAN 1 and the individual information (#2) managed by the individualinformation managing unit 12.

[0095] The information transmitting unit 14 of the mobile terminal MT #2transmits a binding update including the generated location informationto the mobile terminal MT #1, in step 103 a, and transmits the generatedlocation information to the mobility management router 30, in step 103b.

[0096] In step 104 a, the location-in-moving network informationmanaging unit 15 of the mobile terminal MT #1 stores the mobile terminalMT #2 location information.

[0097] In step 104 b, the location information managing unit 32 of themobility management router 30 stores the mobile terminal MT #2 locationinformation.

[0098] From the common information of the mobile terminal MT #2 locationinformation, it can be determined that the mobile terminal MT #2 islocated in the moving network A connected to the access node AN 1.

[0099] In step 105, the notifying unit 33 of the mobility managementrouter 30 gives a notification to the mobile terminals MT #3 and MT #4,so as to instruct them to transmit packets to the mobility managementrouter 30 for communication with the mobile terminal MT #2 located inthe moving network A.

[0100] Second, with reference to FIG. 8, description will be made on anoperation of changing address information (location information) whenthe moving network A moves in the mobile communications system of thisembodiment.

[0101] As shown in FIG. 8, in step 201, the destination access node AN 2transmits an advertisement including common information (AN2prefix)related to the access node AN 2.

[0102] In step 202, the location-in-moving network information managingunit 15 of the mobile terminal MT #1 changes the common information(AN1prefix) of the location information of the mobile terminals MTslocated in the moving network A, to the common information (AN2prefix)included in the advertisement received from the access node AN 2.

[0103] In step 203, the information transmitting unit 14 of the mobileterminal MT #1 transmits an advertisement including the changed commoninformation (AN2prefix), to all the mobile terminals MTs located in themoving network A.

[0104] In step 204, the location-in-moving network information managingunit 15 of the mobile terminal MT #2 changes the common information(AN1prefix) of the mobile terminal MT #2 location information, to thecommon information (AN2prefix) included in the advertisement receivedfrom the mobile terminal MT #1.

[0105] At that time, the information transmitting unit 14 of the mobileterminal MT #2 does not transmit a binding update on the locationinformation, to the mobility management router 30 and the like.

[0106] In step 205, the information transmitting unit 14 of the mobileterminal MT #1 transmits a fact that the moving network A has moved,that is, a binding update for advertising the change of the locationinformation of the mobile terminal MTs located in the moving network A,to the mobility management router 30 (and the mobility management server50).

[0107] In step 206, the location information managing unit 32 of themobility management router 30 changes the common information (AN1prefix)of the location information of the mobile terminal MTs located in themoving network A, to the common information (AN2prefix) included in thebinding update received from the mobile terminal MT #1. As a result, thehandoff process of the mobile terminal MTs located in the moving networkA is completed. <Function/Effect of the Mobile Communications System inthe Embodiment>

[0108] According to the mobile communications system in this embodiment,when the moving network A moves, only common information of locationinformation of the mobile terminals MTs located in the moving network Arelated to an access node AN to which the moving network A is connectedis changed, resulting in a reduced processing time during handoff.

[0109] Further, according to the mobile communications system in theembodiment, only the mobile terminal MT #1 (a given mobilecommunications terminal) located in the moving network A notifies themobility management router 30 and the mobility management server 50, ofthe movement of the moving network A, resulting in a reduced amount ofsignals during handoff process. Specifically, only a signal showing achange of common information is sent, leading to a reduced amount ofsignals during handoff.

[0110] <Mobile Communications System in a Second Embodiment of theInvention>

[0111] With reference to FIGS. 9 to 11, a mobile communications systemaccording to a second embodiment of the present invention will bedescribed. Hereinafter description will be made mainly on differencesfrom the above-described mobile communications system according to thefirst embodiment.

[0112] As shown in FIG. 9, the mobile communications system of thisembodiment is different from the mobile communications system accordingto the first embodiment in that it includes a mobile node MN formanaging a moving network A, and in the configuration of mobile terminalMT location information.

[0113] As shown in FIG. 10, the mobile node MN has an informationreceiving unit 71, a individual information managing unit 72, a locationinformation generating unit 73, an information transmitting unit 74, alocation-in-moving network information managing unit 75, and a movingnetwork controlling unit 76.

[0114] The moving network controlling unit 76 serves as an interfacebetween a mobile terminal MT located in the moving network A and anaccess node AN, cooperating with the location-in-moving networkinformation managing unit 75.

[0115] The other functions of the mobile node MN are identical to thoseof the mobile terminal MT #1 shown in FIG. 4, and will not be described.

[0116] In this embodiment, the common information is mobile node MNaddress information (location information) including information showinga connecting access node AN.

[0117] The individual information is mobile terminal MT addressinformation (location information) including information showing themobile node MN which manages the moving network A where the mobileterminal MT is located.

[0118] More specifically, when the moving network A is connected to anaccess node AN 1, mobile terminal MT #1 address information is“AN1prefixMN (common information)+MNprefix#1 (individual information)”.

[0119] When the moving network A is connected to an access node AN 2,the mobile terminal MT #1 address information is “AN2prefixMN (commoninformation)+MNprefix#1 (individual information)”.

[0120] Likewise, when the moving network A is connected to the accessnode AN 1, mobile terminal MT #2 address information is “AN1prefixMN(common information)+MNprefix#2 (individual information)”.

[0121] When the moving network A is connected to the access node AN 2,the mobile terminal MT #2 address information is “AN2prefixMN (commoninformation)+MNprefix#2 (individual information).”

[0122] Now, with reference to FIG. 11, description will be made on anoperation of changing address information (location information) whenthe moving network A moves in the mobile communications system in thisembodiment.

[0123] As shown in FIG. 11, in step 301, the destination access node AN2 transmits an advertisement including common information (AN2prefixMN)related to the access node AN 2.

[0124] In step 302, the location-in-moving network information managingunit 75 of the mobile node MN changes the common information(AN1prefixMN) of the location information of the mobile terminal MTslocated in the moving network A, to the common information (AN2prefixMN)included in the advertisement received from the access node AN 2.

[0125] In step 303, the information transmitting unit 74 of the mobilenode MN transmits an advertisement including the changed commoninformation (AN2prefixMN), to all the mobile terminals MTs located inthe moving network A.

[0126] In step 304, location-in-moving network information managingunits 15 of the mobile terminals MT #1 and MT #2 change the commoninformation (AN1prefixMN) of the location information of the mobileterminals MT #1 and MT #2, to the common information (AN2prefixMN)included in the advertisement received from the mobile node MN.

[0127] At that time, information transmitting units 14 of the mobileterminals MT #1 and MT #2 do not transmit a binding update on thelocation information to a mobility management router 30 and the like.

[0128] In step 305, the information transmitting unit 74 of the mobilenode MN transmits a binding update for advertising that the movingnetwork A has moved, that is, the change of the location information ofthe mobile terminals MTs located in the moving network A, to themobility management router 30 (and a mobility management server 50).

[0129] In step 306, a location information managing unit 32 of themobility management router 30 changes common information (AN1prefixMN)of location information of the mobile terminals MTs located in themoving network A, to the common information (AN2prefixMN) included inthe binding update received from the mobile node MN. As a result, thehandoff process of the mobile terminals MTs located in the movingnetwork A is completed.

[0130] According to the mobile communications system in this embodiment,when the moving network A moves, only common information related to anaccess node AN to which the moving network A is connected, of locationinformation of the mobile terminals MTs located in the moving network Ais changed, resulting in a reduced processing time during handoffprocess.

[0131] Further, according to the mobile communications system in thisembodiment, only the mobile node MN located in the moving network Anotifies the mobility management router 30 and the mobility managementserver 50, of the movement of the moving network A, resulting in areduced amount of signals during handoff process. Specifically, only asignal showing a change of common information is sent, leading to areduced amount of signals during handoff process.

[0132] <Mobile Communications System in a Third Embodiment of theInvention>

[0133] With reference to FIGS. 12 and 13, a mobile communications systemaccording to a third embodiment of the present invention will bedescribed. The mobile communications system in this embodiment is theresult of application of the above-described mobile communicationssystem in the second embodiment to a conventional HMIP mobilecommunications system.

[0134] Hereinafter description will be made mainly on differences fromthe mobile communications system in the second embodiment.

[0135] As shown in FIG. 12, the mobile communications system in thisembodiment is different from the mobile communications system in thesecond embodiment, in the configuration of mobile terminal MT locationinformation.

[0136] Specifically, when a moving network A is connected to an accessnode AN 1, mobile terminal MT #1 routing information (locationinformation) is “CoA_MN (under AN 1)” (first routing information) in aMAP (see FIG. 13A), and is “CoA_MT1” (second routing information) in amobile node MN (see FIG. 13B).

[0137] When the moving network A is connected to an access node AN 2,the mobile terminal MT #1 routing information (location information) is“CoA_MN (under AN 2)” (first routing information) in the MAP, and is“CoA_MT1” (second routing information) in the mobile node MN.

[0138] Also, when the moving network A is connected to the access nodeAN 1, mobile terminal MT #2 routing information (location information)is “CoA_MN (under AN 1)” (first routing information) in the MAP (seeFIG. 13A), and is “CoA_MT2” (second routing information) in the mobilenode MN (see FIG. 13B).

[0139] When the moving network A is connected to the access node AN 2,the mobile terminal MT #2 routing information (location information) is“CoA_MN (under AN 2)” (first routing information) in the MAP, and is“CoA_MT2” (second routing information) in the mobile node MN.

[0140] Specifically, as shown in FIG. 13A, the mobile node MN addressinformation (care-of-address) is used as the first mobile terminal MTrouting information.

[0141] As shown in FIG. 13B, the mobile terminal MT address information(care-of-addresses) is used as the second mobile terminal MT routinginformation.

[0142] When detecting the movement of the moving network A, aninformation transmitting unit 74 of the mobile node MN transmits abinding update showing the fact to the MAP.

[0143] As a result, a location information managing unit 32 of the MAPchanges the routing information on the mobile terminals MTs located inthe moving network A.

[0144] In this embodiment, the above described “CoA_MN” is the commoninformation in the moving network A. Therefore, the address informationof the mobile communications terminals can be changed, only by changingthe common information (“CoA_MN”), when the handoff process isperformed.

[0145] <Mobile Communications System in a Fourth Embodiment of theInvention>

[0146] With reference to FIG. 14, a mobile communications systemaccording to a fourth embodiment of the present invention will bedescribed. The mobile communications system in this embodiment shows anexemplary method of assigning common information and individualinformation.

[0147] As shown in FIG. 12, the mobile communications system in thisembodiment is comprised of a hierarchical structure including nodes Node#1 to Node #3, access nodes AN 1 to AN 4, and a mobile node MN.

[0148] As shown in FIG. 14, the Node #1 is assigned a subnetwork“A::/10”, the Node #2 is assigned a subnetwork “A.A::/20”, the Node #3is assigned a subnetwork “A.B::/20”, the access node AN 1 is assigned asubnetwork “A.A.A::/30”, the access node AN 2 is assigned a subnetwork“A.A.B::/30”, the access node AN 3 is assigned a subnetwork“A.B.A::/30”, and the access node AN 4 is assigned a subnetwork“A.B.B::/30”. Here, IP v6 notation is used for the indication of thesubnetworks.

[0149] The mobile node MN connected to the access node AN 1 is assigneda portion (A.A.A.A::/40) of the subnetwork assigned to the access nodeAN 1 as common information by the access node AN 1.

[0150] <Mobile Communications System in a Fifth Embodiment of theInvention>

[0151] With reference to FIGS. 15 to 19, a mobile communications systemaccording to a fifth embodiment of the present invention will bedescribed. Hereinafter description will be made mainly on differencesfrom the above-described mobile communications system according to thesecond embodiment.

[0152] As shown in FIG. 15, the mobile communications system in thisembodiment is different from the mobile communications system in thesecond embodiment in that it includes a network management server NCPFand in that address conversion is performed in a mobility managementrouter (AGR) 30, an access node AN and a mobile node MN.

[0153] Use of this system allows individual information to be limited inuse to a moving network, thus prevented from duplication, and reliablyunchanged when the moving network moves.

[0154] With reference to FIG. 16, the configuration of the networkmanagement server NCPF will be described. As shown in FIG. 16, thenetwork management server NCPF has a location information managing unit81, a routing table managing unit 82, an information receiving unit 83,and an information transmitting unit 84.

[0155] The location information managing unit 81 manages locationinformation of all mobile terminals MTs located in a moving network A.

[0156] In the example of FIG. 16, the location information managing unit81 manages mobile terminal MT #1 location information including “commoninformation=IPraAN1(MN)” and “individual information=#MT1”, and mobileterminal MT #2 location information including “commoninformation=IPraAN1(MN)” and “individual information=#MT2”, and so on.

[0157] The routing table managing unit 82 manages a routing table forperforming address conversion in a core network 1 (that is, in theaccess nodes ANs and the mobility management router 30) and in a mobilenode MN.

[0158] The information receiving unit 83 receives various informationincluding a binding update from a mobile node MN. The informationtransmitting unit 84 transmits various information such as a bindingupdate on address conversion tables, to a mobile node MN, the mobilitymanagement router (AGR) 30 and the access nodes ANs.

[0159] In the example of FIG. 15, an address conversion table of anaccess node AN 3 is for converting a home address HoA (IPha#MT1) of themobile terminal MT #1 into first mobile terminal MT #1 locationinformation RA#1 (IPraAGR#MT1).

[0160] An address conversion table of the mobility management router(AGR) 30 is for converting first common information (prefix: IPraAGR) ofthe first mobile terminal MT #1 location information RA#1 (IPraAGR#MT1)into second common information (prefix: IPraAN1(MN)) of second mobileterminal MT #1 location information RA #2 (IPraAN1(MN)#MT1).

[0161] Here, the mobility management router (AGR) 30 uniformly convertsthe first common information “IPraAGR” included in received packets intothe second common information “IPraAN1(MN)”.

[0162] During handoff process of the moving network A, the mobilitymanagement router (AGR) 30 only rewrites the second common informationinstead of rewriting individual location information of the mobileterminals MTs located in the moving network A, resulting in asignificant reduction in processing time during handoff process.

[0163] An address conversion table of the mobile node MN is forconverting the second mobile terminal MT #1 location information RA#2(IPraAN1(MN)#MT1) into the home address HoA (IPha#MT1) of the mobileterminal MT #1.

[0164] Now, with reference to FIGS. 17 to 19, the operation of themobile communications system according to this embodiment will bedescribed.

[0165] First, with reference to FIG. 17, a registration operation of themobile terminal MT #1 in the mobile communications system according tothis embodiment will be described.

[0166] As shown in FIG. 17, in step 401, an access node AN 1 transmitsan advertisement to the mobile node MN.

[0167] In step 402, an information transmitting unit 74 of the mobilenode MN transmits to the access node AN 1 an inquiry for commoninformation (prefix) assignable to the mobile terminal MT #1 located inthe moving network A.

[0168] In step 403, the access node AN 1 selects a prefix (commoninformation) assignable to the mobile terminal MT #1, and in step 404,the access node AN 1 transmits a reply including the selected prefix(common information) to the mobile node MN.

[0169] In step 405, the information transmitting unit 74 of the mobilenode MN transmits to the mobile terminal MT #1 an advertisement showingthe fact that the mobile terminal MT #1 can be registered. In step 406,the mobile terminal MT #1 transmits a reply to the advertisement to themobile node MN.

[0170] In step 407, a location information generating unit 73 of themobile node MN generates mobile terminal MT #1 location information(“common information=IPraAN1(MN)”+“individual information=#MT1”)according to the prefix (common information), and stores the generatedmobile terminal MT #1 location information in a location-in-movingnetwork information managing unit 75 (address conversion table).

[0171] In step 408, the information transmitting unit 74 of the mobilenode MN notifies the network management server NCPF of the generatedmobile terminal MT #1 location information.

[0172] In step 409, the location information managing unit 81 of thenetwork management server NCPF stores the mobile terminal MT #1 locationinformation, and the routing table managing unit 82 updates the addressconversion table (related to the prefix) of the mobility managementrouter (AGR) 30 optimally selected in view of the moving characteristicsof the moving network A.

[0173] In step 410, the information transmitting unit 84 of the networkmanagement server NCPF transmits information for creating an addressconversion table related to the prefix, to the mobility managementrouter (AGR) 30.

[0174] In step 411, a location information managing unit 31 of themobility management router (AGR) 30 creates an address conversion tablerelated to the prefix according to the information from the networkmanagement server NCPF.

[0175] In step 412, an information transmitting unit 31 transmits areply showing the completion of creation of the address conversiontable, to the network management server NCPF.

[0176] In step 413 a, the network management server NCPF transmits abinding update including the mobile terminal MT #1 location informationto the mobile node MN, and in step 413 b, the network management serverNCPF transmits the binding update to the mobility management router(AGR) 30.

[0177] In step 414, the location-in-moving network information managingunit 75 of the mobile node MN completes the update of mobile terminal MT#1 location information, and informs the mobile terminal MT #1 of thefact in reply. Then, the mobile terminal MT #1 can perform communicationin the moving network A.

[0178] Second, with reference to FIG. 18, a packet transfer operation inthe mobile communications system in this embodiment will be described.

[0179] As shown in FIG. 18, in step 501, a mobile terminal MT #3transmits packets including “IPha#MT1 (the home address of the mobileterminal MT #1)” as a destination address, to an access node AN 3.

[0180] In step 502, the access node AN 3 transmits an inquiry to thenetwork management server NCPF for the first mobile terminal MT #1routing information. In step 503, the information transmitting unit 84of the network management server NCPF transmits a binding update forupdating the address conversion table of the access node AN 3, to theaccess node AN 3.

[0181] In step 504, the access node AN 3 updates the address conversiontable according to the received binding update, and converts thedestination address of the received packets, into “IPraAGR#MT1 (a firstrouting address of the mobile terminal MT #1)”. In step 505, the accessnode AN 3 transfers the packets with the converted address to themobility management router (AGR) 30.

[0182] In step 506, a routing processing unit 34 of the mobilitymanagement router (AGR) 30 converts the destination address of thereceived packets into “IPraAN1(MN)#MT1 (a second routing address of themobile terminal MT #1) ”, referring to the address conversion table, andin step 507, the routing processing unit 34 transfers the packets withthe converted address to the mobile node MN.

[0183] In step 508, the mobile node MN converts the destination addressof the received packets into “IPha#MT1 (the home address of the mobileterminal MT #1)”, referring to the address conversion table, and in step509, the mobile node MN transfers the packets with the converted addressto the mobile terminal MT #1.

[0184] Third, with reference to FIG. 19, an operation of changing mobileterminal MT #1 address information (location information) in the mobilecommunications system according to this embodiment will be described.

[0185] As shown in FIG. 19, in step 601, the mobile terminal MT #1 iscommunicating with the mobile terminal MT #3.

[0186] In step 602, when the moving network A moves, the informationtransmitting unit 74 of the mobile node MN transmits an inquiry to thedestination access node AN 2 for a prefix (common information)assignable to the mobile terminals MTs located in the moving network A.

[0187] In step 603, the access node AN 2 selects a prefix (commoninformation) assignable to the mobile terminals MTs located in themoving network A, and in step 604, the access node AN 2 sends theselected prefix (common information) to the mobile node MN in response.

[0188] In step 605, the location-in-moving network information managingunit 75 of the mobile node MN changes common information of locationinformation of all the mobile terminals MTs located in the movingnetwork A according to the selected prefix (common information).

[0189] In step 606, the information transmitting unit 74 of the mobilenode MN transmits a notification that the location information of allthe mobile terminals MTs located in the moving network A has beenchanged, to the network management server NCPF.

[0190] Here, only a signal showing that the common information has beenchanged is sent, resulting in a reduced amount of signals during handoffprocess.

[0191] In step 607, the location information managing unit 81 and therouting table managing unit 82 of the network management server NCPFchange the common information of the location information of all themobile terminals MTs located in the moving network A.

[0192] In step 608 a, the information transmitting unit 84 of thenetwork management server NCPF transmits to the mobile node MN a bindingupdate on the location information of all the mobile terminals MTslocated in the moving network A, and in step 608 b, the informationtransmitting unit 84 transmits the binding update to the mobilitymanagement router (AGR) 30.

[0193] In step 609, the mobility management router (AGR) 30 updates theaddress conversion table in a location information managing unit 32according to the received binding update, and in step 610, the mobilitymanagement router (AGR) 30 informs, in reply, the network managementserver NCPF of the completion of update of the address conversion table.

[0194] In step 611, the information transmitting unit 84 of the networkmanagement server NCPF transmits an instruction to the left access nodeAN 1 to delete the location information of all the mobile terminals MTslocated in the moving network A.

[0195] Instep 612, the access node AN 1 deletes the corresponding recordfrom an address conversion table according to the deletion instructionfrom the network management server NCPF. In step 613, the access node AN1 transmits a reply showing the completion of the deletion, to thenetwork management server NCPF.

[0196] As described above, the present invention can provide a mobilecommunications system, a mobile communications method, a server, atransfer device and a mobile communications terminal for supportingmoving networks, which allow significant reductions in the amount ofsignals and processing time during handoff process.

[0197] Additional advantages and modifications will readily occur tothose skilled in the art. Therefore, the invention in its broaderaspects is not limited to the specific details and the representativeembodiment shown and described herein. Accordingly, variousmodifications may be made without departing from the spirit or scope ofthe general inventive concept as defined by the appended claims andtheir equivalents.

What is claimed is:
 1. A mobile communications system for transferringpackets to a mobile communications terminal according to addressinformation of the mobile communications terminal, the mobilecommunications terminal being located in a moving network connected to agiven node in a core network, wherein: the address information of themobile communications terminal comprises: common information related tothe given node to which the moving network is connected; and individualinformation which is unrelated to the given node to which the movingnetwork is connected and which is unchanged when the connection to thegiven node to which the moving network is connected is changed toanother node.
 2. A mobile communications method of transferring packetsto a mobile communications terminal according to address information ofthe mobile communications terminal, the mobile communications terminalbeing located in a moving network connected to a given node in a corenetwork, wherein the address information of the mobile communicationsterminals comprises common information related to the given node towhich the moving network is connected and individual informationunrelated to the given node to which the moving network is connected;and the method comprising the steps of: detecting a change of the givennode to which the moving network is connected, in a given mobilecommunications terminal located in the moving network; changing theaddress information of all mobile communications terminals located inthe moving network, only by changing common information of the addressinformation of the mobile communications terminals, in the given mobilecommunications terminal; notifying the mobile communications terminalslocated in the moving network, of the change of the address informationof the mobile communications terminals, in the given mobilecommunications terminal; and notifying an address management deviceconfigured to manage address information of the mobile communicationsterminals located in the moving network of the change, in the givenmobile communications terminal.
 3. A mobile communications method oftransferring packets to a mobile communications terminal according toaddress information of the mobile communications terminal, the mobilecommunications terminal being located in a moving network connected to agiven node in a core network, wherein the address information of themobile communications terminals comprises common information related tothe given node to which the moving network is connected and individualinformation unrelated to the given node to which the moving network isconnected; and the method comprising the steps of: notifying a mobilenode configured to manage the moving network of common informationrelated to the given node, in the given node; changing the addressinformation of all mobile communications terminals located in the movingnetwork, only by changing common information of the address informationof the mobile communications terminals according to the notified commoninformation, in the mobile node; and notifying an address managementdevice configured to manage the address information of the mobilecommunications terminals in the moving network, of the change of theaddress information of the mobile communications terminals, in themobile node.
 4. A server in a mobile communications system fortransferring packets to mobile communications terminals according toaddress information of the mobile communications terminal, the mobilecommunications terminals being located in a moving network connected toa given node in a core network, the server comprising: an addressinformation manager configured to manage the address information of allmobile communications terminals located in the moving network; andwherein the address information of the mobile communications terminalscomprise: common information related to the given node to which themoving network is connected; and individual information which isunrelated to the given node to which the moving network is connected andis unchanged when the connection to the given node to which the movingnetwork is connected is changed to another node.
 5. The server as setforth in claim 4, wherein the address information manager changes onlythe common information according to a notification from a given mobilecommunications terminal located in the moving network or a mobile nodeconfigured to manage the moving network.
 6. A transfer device providedon a packet transfer path in a mobile communications system fortransferring packets to a mobile communications terminal according toaddress information of the mobile communications terminal, the mobilecommunications terminal being located in a moving network connected to agiven node in a core network, the transfer device comprising: an addressinformation manager configured to relate the address information of themobile communications terminal located in the moving network; whereinthe address information of the mobile communications terminal includescommon information related to the given node to which the moving networkis connected and individual information unrelated to the given node towhich the moving network is connected.
 7. The transfer device as setforth in claim 6, wherein: the address information manager changes theaddress information of the mobile communications terminals, only bychanging the common information according to a notification from a givenmobile communications terminal located in the moving network or a mobilenode configured to manage the moving network.
 8. The transfer device asset forth in claim 6, further comprising an address converter configuredto convert first common information of the address information of themobile communications terminal, into second common information of theaddress information of the mobile communications terminal, withinreceived packets; and wherein the address information manager relatesthe first common information to the second common information.
 9. Amobile communications terminal in a mobile communications system fortransferring packets to mobile communications terminals located in themoving network connected to a given node in a core network according toaddress information of the mobile communications terminals, the mobilecommunications terminal comprising: an address information managerconfigured to manage the address information of the mobilecommunications terminals located in the moving network; wherein theaddress information of the mobile communications terminals comprisescommon information related to the given node to which the moving networkis connected and individual information unrelated to the given node towhich the moving network is connected.
 10. The mobile communicationsterminal as set forth in claim 9, wherein: when detecting a change ofthe given node to which the moving network is connected, the addressinformation manager changes the address information of the mobilecommunications terminal, only by changing the common information; andthe address information manager notifies an address management deviceconfigured to manage the address information of the mobilecommunications terminal located in the moving network, of the change ofthe address information of the mobile communications terminal.